It is known from the state of the art that a user can indicate his acceptance of the charges of a telephone call if an operator switches the call. In that case the acceptance of the charges of a telephone call to be established can be verbally agreed with the telephone network operator.
The acceptance of the charges by the called party in an ISDN telephone network is also known. The January 1994 DE-NA-10017 ETSI publication "Integrated Services Digital Network" explains the method when the ISDN telephone network is used. In that case the user can preselect permanent connections for which the cost acceptance has been agreed with the network operator. But it also possible to signal a cost acceptance when such a service has been requested by the caller. The user must then present his user identification to the network operator through a password which is entered into the telephone set in the form of a combination of numbers. This cost acceptance service must be designed for the individual user. In the fixed ISDN network the cost acceptance function is restricted to a predetermined subscriber line.
A telephone installation is known from DE-OS 42 22 235, where the terminals are operated by a chip card. The chip card contains a personal account number for the applicable fee, which is coordinated by comparing it to a data base in the telephone installation. The individual terminals can only be operated if the personal account number authorizes the respective user to establish a connection. To carry out the method, the telephone terminals contain a card reading unit which is able to read the information stored on a chip card.
Also known is the use of so-called SIM (Subscriber Identity Module) cards for use in GSM radio telephone networks. These cards contain a personal identification number, an algorithm and a personal subscriber code for producing an authentication information which is transmitted to a central station where it is checked for the user's authorization. The use of the known chip cards makes it possible to establish connections but not to accept the charges, which are only created by a call from a third party.